The cardiovascular system, which is composed of the heart and blood vessels, is essential for the distribution of oxygen, nutrients, and other critical components to all organs throughout the horse’s body. As the heart is the sole pump for the cardiovascular system, any disruption of its function can have critical consequences for the animal’s life.
The term “heart attack” has incorrectly evolved into common usage to refer to sudden death associated with heart disease. To medical professionals for people, this term is specifically reserved for myocardial infarction. In people, myocardial infarcts are commonly caused by clogged blood vessels that reduce blood flow to the heart and result in damage or death to the heart muscle.
Since horses do not routinely suffer from coronary artery disease, “heart attacks” in this sense rarely occur. Racehorses that unexpectedly drop dead due to sudden death syndrome (Swale syndrome) are frequently said to have died of a “heart attack.” This determination, however, is inaccurate, as heart lesions may not be present, so use of the term “heart attack” is imprecise.